Multi-omics reveals growth regulatory mechanisms induced by exogenous TgSWO expansin-like protein in strawberry

Expansin-like proteins from Trichoderma have emerged as potential biological regulators of plant growth through their effects on cell wall properties; however, the molecular mechanisms underlying their growth-promoting effects in horticultural crops remain poorly understood.

This study investigated the effects of TgSWO, an expansin-like protein from Trichoderma harzianum NJAU 4742, on strawberry (Fragaria × ananassa) root development and elucidated the underlying regulatory mechanisms. Strawberry plantlets were treated with 0, 15, or 30 μM TgSWO for 2 weeks, followed by root phenotypic characterization, transmission electron microscopy, transcriptomic profiling, and untargeted metabolomic analysis.

Exogenous TgSWO application significantly promoted strawberry root development, as evidenced by increased root number, root fresh weight, root length, root surface area, and root tip number. Transmission electron microscopy revealed that TgSWO treatment altered root cell morphology, indicating enhanced cellular remodeling. Transcriptomic analysis showed that low-dose TgSWO treatment primarily enhanced metabolic activity and cell wall remodeling, whereas high-dose TgSWO treatment activated redox regulation, secondary metabolism, and structural reinforcement pathways. Metabolomic analysis further demonstrated that TgSWO reshaped root metabolic profiles by regulating pathways associated with nutrient uptake, lipid metabolism, amino acid metabolism, and secondary metabolism. Key metabolites positively correlated with root biomass, including cinnamic acid and cysteine, were identified as potential contributors to TgSWO-mediated root growth promotion.

These findings reveal that TgSWO promotes strawberry root development through coordinated regulation of cell wall remodeling, transcriptional reprogramming, and metabolic adjustment, providing new insights into microbial expansin-like protein-mediated plant growth regulation and supporting the potential application of TgSWO as a functional protein-based strategy for greenhouse strawberry production.